a) b) [² c) Deu Peu 7-The all day efficiency of a transformer depends primarily on a) It's copper loss 9 9 b) The amount load c) The duration of load. d) Both (b) and (c) 8-A single-phase, 2200/200 V transformer takes 1 A at the H.V side on no load at a power factor of 0.23 lagging. The magnetizing current is a) 0.46 A 50.973 A c) 0.23 A d) 0.5 A (16 marks) (B)-Draw the connection diagram of three-phase transformer with Y-D connection and give the mathematical relationships of line and phase (voltage, current) for both sides, and out power (kW) (5 marks) nestivaly Its full load

A 23/230-kV step-up transformer feeds a three-phase transmission line, which in turn supplies a 150-MVA,0.8 lagging power factor load through a step-down 230/23-kV transformer. The impedance of the line and transformers at 230kVis18+j60. Determine the tap setting for each transformer to maintain the voltage at the load at 23 kV.

The symbol shown is a(n) a. iron core transformer. b. auto transformer. c. current transformer. d. air core transformer.

A single-phase, 120V(rms),60Hz source supplies power to a series R-L circuit consisting of R=10 and L=40mH. (a) Determine the power factor of the circuit and state whether it is lagging or leading. (b) Determine the real and reactive power absorbed by the load. (c) Calculate the peak magnetic energy Wint stored in the inductor by using the expression Wint=L(Irms)2 and check whether the reactive power Q=Wint is satisfied. (Note: The instantaneous magnetic energy storage fluctuates between zero and the peak energy. This energy must be sent twice each cycle to the load from the source by means of reactive power flows.)

A single-phase, 50-kVA,2400/240-V,60-Hz distribution transformer has the following parameters: Resistance of the 2400-V winding: R1=0.75 Resistance of the 240-V winding: R2=0.0075 Leakage reactance of the 2400-V winding: X1=1.0 Leakage reactance of the 240-V winding: X2=0.01 Exciting admittance on the 240-V side =0.003j0.02S (a) Draw the equivalent circuit referred to the high-voltage side of the transformer. (b) Draw the equivalent circuit referred to the low-voltage side of the transformer. Show the numerical values of impedances on the equivalent circuits.

For an ideal transformer, the efficiency is (a) 0 (b) 100 (c) 50

All values of a transformer are proportional to its __________________ ___________________.

For an ideal 2-winding transformer, an impedance Z2 connected across winding 2 (secondary) is referred to winding 1 (primary) by multiplying Z2 by (a) The turns ratio (N1/N2) (b) The square of the turns ratio (N1/N2)2 (c) The cubed turns ratio (N1/N2)3

In a transformer that has 10 times more turns on the secondary side (side 2) than on the primary side (side 1), the magnitude of the voltage/EMF across the windings on the secondary side, E₂ will be... O a.... 10 times lower than the voltage/emf on the primary side, E₁. O b.... the same as the voltage/emf on the primary side. O c.... always zero regardless of the voltage on the primary side, E₁. O d.... 10 times higher than the voltage/emf on the primary side, E₁.

The efficiency of a transformer at load 0.8 p.f. Lag is -- at load 0.8 p.f. Lead * equal less than more than none of these